Methamphetamine use disorders among New Zealand prisoners
Principal Research Adviser, Department of Corrections
Jill joined the Department of Corrections’ Research and Analysis Team in 2010. She manages a variety of research and evaluation projects, and has a particular interest in desistance, employment outcomes of released prisoners, how probation officers work with offenders and the needs of female offenders. As well as working for Corrections, she volunteers at Arohata Prison, teaching quilting to the women in the Drug Treatment Unit.
A 2015 study of mental health and substance abuse disorders among New Zealand prisoners found that the prevalence of methamphetamine disorders had increased almost 10-fold since a similar study was conducted in 1999. A Practice article by the author reported on the overall results from this study (Bowman, 2016).
Given the significant harms and increased mental illness attributable to the use of methamphetamine, the Department of Corrections contracted the Australian research consortium that had analysed the data from the 2015 study to conduct further analysis, focusing on methamphetamine use. The purpose of this additional work was to better understand the mental health, comorbidity, treatment seeking and other associated factors for prisoners with and without a methamphetamine use disorder, and to inform programmes the department has recently implemented to assist prisoners with a methamphetamine use disorder.
Between March and July 2015, 1,209 offenders in 13 New Zealand prisons were interviewed about their mental health issues and substance abuse.
The prisoners who participated in the study had either been sentenced within the three months preceding their interview or were remand-convicted prisoners, so their responses were based on their experiences while in the community. In addition, interviewers reminded participants that their responses should reflect the period before their admission to prison.
The full methodology for carrying out the research was described in a Practice article by the author (Bowman, 2015).
Findings about methamphetamine use
Significant findings from the research included:
- a high level of methamphetamine use amongst prisoners
- high levels of comorbidity with a mental disorder or abuse of other substances amongst prisoners with a methamphetamine disorder
- the earlier occurrence of mental health issues for prisoners with both a mental health disorder and a methamphetamine disorder.
These and other key findings are discussed below.
The analysis revealed a high use of methamphetamine amongst New Zealand prisoners. Over half of all prisoners (56%) had used methamphetamine at some time during their lives and, of those who had used it, over half (58%) had used it in the previous 12 months. More male prisoners had used methamphetamine over their lifetimes than female prisoners (56% compared with 49%), but women were more likely to have used it within the preceding 12 months (67% compared with 57%). There were no significant ethnicity differences in methamphetamine use.
Over a third of prisoners (38%) had abused methamphetamine (that is, it had caused problems in their lives) or had a dependency over their lifetimes, with males more likely to have an abuse disorder (16% compared with 6%) but females more likely to have a dependence disorder (32% compared with 23%)**. Over the last 12 months, 16% of prisoners had a methamphetamine abuse disorder (3%) or a dependence disorder (13%). This is much lower than was found in a 2001 Australian study of 1,500 prisoners (27%), using the same diagnostic tools. As with the lifetime disorder figures, women were more likely than men to have a 12-month dependence disorder (19% compared with 12%).
Both abuse and dependence on methamphetamine was highest among prisoners aged 25-44 years, but younger prisoners used methamphetamine for the first time earlier than older prisoners. Those aged between 17 and 24 years first used the drug at the age of 16.8 years, compared with 25 to 44 year olds who first used it at 20.8 years, and those aged 45 years and older who first used it at 29.8 years. There was no significant difference in age of first use between men and women or between ethnicities.
Lifetime methamphetamine dependence was found to be most prevalent among prisoners whose first imprisonment occurred at a younger age, who had spent more time in prison and had more custodial sentences.
With regard to types of offending, prisoners with a lifetime methamphetamine dependence disorder were more likely to have a current offence related to drugs or burglary, and offenders who had used methamphetamine in the last year were more likely to have a current burglary offence. This suggests that the prisoners were under the influence of methamphetamine when they committed their offence, or they had committed the offence to enable them to obtain methamphetamine.
Compared with prisoners without a methamphetamine dependence disorder, prisoners with a lifetime dependence disorder were nearly twice as likely to have a comorbidity with another substance use or a mental disorder. They also had a significantly higher prevalence of most anxiety or mood disorders than prisoners without a methamphetamine dependence disorder. The age of onset of the mental health disorder in prisoners who had a comorbid anxiety or mood disorder always occurred before the age of onset of the methamphetamine disorder. This suggests that prisoners with these mental health disorders are at a higher risk of substance use disorders and may be self-medicating with methamphetamine and other substances.
There was no association between methamphetamine dependence and the presence of psychosis symptoms for either a lifetime or 12-month diagnosis. However, it should be noted that the psychosis screener in the tool used in the study is not a diagnostic instrument.
Most prisoners with a methamphetamine dependence also used other drugs, and they were three times more likely (58% compared with 18%) to have another drug dependence than prisoners who did not have a methamphetamine dependence. The age of onset of the methamphetamine dependence compared with the age of onset of the other drug dependence varied, depending on what the other drug was. Prisoners with a dependence on alcohol, marijuana, inhalants and hallucinogens had an earlier age of onset for these drugs than the age of onset for their methamphetamine dependence, lending credence to the “gateway” theory of drug use. For all other substance dependence comorbidities (for example, club drugs, cocaine, opiates, painkillers, and sedatives), the methamphetamine dependence occurred at an earlier age than the dependence on the other drugs.
The following tables summarise the findings from the report. However, the full report Impact of stimulant dependence on the mental health of New Zealand prisoners is available on Corrections’ website www.corrections.govt.nz
Summary of findings
Table i. Correlates of stimulant use and disorders
|% ever use stimulants||% use stimulants in past year||Stimulant abuse disorder (%)||Stimulant dependence disorder (%)|
Country of birth
Time in custody
Age first time in
† Statistically significant (P<0.05)
Table ii. Comorbidities by stimulant dependence disorders
|12-month diagnosis||Lifetime diagnosis|
|No stimulant dependence % (n=1035)||Stimulant dependence % (n=174)|| No stimulant dependence % |
| Stimulant dependence % |
Generalised anxiety disorder
Post-traumatic stress disorder
Any anxiety disorder
Major depressive disorder
Any mood disorder
Other drug abuse*
Other drug dependence*
Three or more disorders
Any eating disorder
Psychological distress (past 30 days)
Any personality disorder
Any mental health treatment (past year)
†Statistically significant (P<0.05); *Excluding stimulants
Implications for Corrections’ practice
These findings suggest the need to intervene early with young people who have a mental health disorder or an issue with alcohol or “softer” drugs to prevent their moving on to methamphetamine or other more serious drugs. The results also highlight the need to treat the drug and alcohol and mental health needs of all prisoners together.
The Department has expanded its mental health interventions to improve the treatment and care of offenders (both in prison and in the community) who have mild-moderate mental health needs.
In addition, specific measures to assist prisoners with methamphetamine abuse have recently been introduced. These include immediate help to remand prisoners who are identified as having methamphetamine problems plus referrals to longer term treatment options, as well as a methamphetamine elective option as part of the drug treatment programmes in prison. A new burglary treatment programme being developed by Corrections offers opportunities to deal with the apparent relationship between burglary offences and methamphetamine dependence.
These findings suggest areas where further research would be useful, including exploring the reasons for commencing methamphetamine use and the pathways people take to its use. In addition, a better understanding of how people acquire the drug, and the relationship between offending and drug use would be useful.
** Simply put, abuse reflects “too much, too often” and dependence is the inability to cease methamphetamine use.
Bowman, J. (2015) Comorbidity research – Part one. Practice, The New Zealand Corrections Journal, Vol 3, Issue 2, 33 – 34, Department of Corrections
Bowman, J. (2016) Comorbid substance use disorders and mental health disorders among New Zealand prisoners. Practice, The New Zealand Corrections Journal, Vol 4, Issue 1, 15 – 20, Department of Corrections